Problem Description: Getting accurate location data for the NIMS nodeProblem Description: Getting accurate location data for the NIMS node

Proposed Solution: Separate encoder module Proposed Solution: Separate encoder module

Introduction: Networked Infomechanical Systems (NIMS)Introduction: Networked Infomechanical Systems (NIMS)

What is NIMS?• NIMS is a sensor network which is composed

of both mobile nodes and static nodes• Designed to access remote environments

which are inaccessible by conventional means• NIMS contains various data sensors which

monitor the surrounding environment on a 24 hour basis

• Different sensors include temperature sensors, light sensors, humidity sensors, and a camera.

Importance of Accurate Position Readings• Collision Avoidance

– If the position of an obstacle is known, the node must be able to avoid collision with the obstacle.

• Reproducible movements– Environmental experiments require the node to

repeatedly collect data at the same location at different times.

• Autonomous movement of the node– Ability to run algorithms without human assistance

Previous Method Proved Unreliable

 

Encoder module Encoder Software Architecture

Center for Embedded Networked SensingCenter for Embedded Networked Sensing

UCLA – UCR – Caltech – USC – CSU – JPL – UC MercedUCLA – UCR – Caltech – USC – CSU – JPL – UC Merced

Roja Bandari, Wendy Gwo, Rachel Scollans, Richard Pon, and Professor William KaiserNIMS

Reliable Actuation for Networked Infomechanical Reliable Actuation for Networked Infomechanical SystemsSystems

• Position obtained from motor – Motor uses resolver feedback to monitor position.

• Slipping of drive wheels on the cable– The actual distance traveled by the node was different

from the data reported by the motor because of the slipping.

• Pendulum movement– Stacking modules vertically under the main node

causes undesirable oscillation and slippage

• Addition of an encoder module– The accurate position data is acquired by an optical encoder – The encoder is enclosed in a separate module – The module is dragged or pushed by the main node on the cable.– The module runs on idler wheels connected to the encoder pulley– This setup makes a train-like structure to reduce the pendulum

movement • The Encoder

– Optical encoder– IP67 splash rating

• The Design– Stainless steel idler wheels connected to the encoder via timing belt– Tension wheels to increase friction and reduce slipping– Thinner walls to reduce overall weight of node

NIMS Applications•Allows for complex algorithm development including image processing, collision detection and avoidance, and sensing uncertainty•Allows for long term observation of various natural environmental conditions•Enhances educational programs in the scientific community

•Coordination of Encoder and Current Motor System

Reliable Actuation

Motor Driver Encoder Driver

Feedback: absolute position

Sends move commands:currently not using motor feedback

•Functionality

•Absolute movement•Relative movement•xy movement•movement in both steps and meters•boundary checking

•Features

•Dual Channel Quadrature Encoder•RS-232•Compact•On board network address switch•Programmable counting directions

Idler Wheel

Tension Wheel

Encoder

Timing Belt Pulley

The Module